High-Mass MALDI-MS Using Ion Conversion Dynode Detectors: Influence of the Conversion Voltage on Sensitivity and Spectral Quality
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With the development of special ion conversion dynode (ICD) detectors for high-mass matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), the mass-to-charge ratio is no longer a limiting factor. Although these detectors have been successfully used in the past, there is lack of understanding of the basic processes in the detector. We present a systematic study to investigate the performance of such an ICD detector and separate the contributions of the MALDI process from the ones of the ion-to-secondary ion and the secondary ion-to-electron conversions. The performance was evaluated as a function of the voltages applied to the conversion dynodes and the sample amount utilized, and we found that the detector reflects the MALDI process correctly: limitations such as sensitivity or deviations from the expected signal intensity ratios originate from the MALDI process itself and not from the detector.
KeywordsMALDI-ToF-MS High-mass protein analysis Ion conversion dynode Sensitivity Resolution
The authors thank the SystemsX.ch initiative (CINA grant) and the Swiss National Science Foundation (grant no. 200020-124663) for financial support, and Nadezhda Nespovitaya for her help with the expression and purification of the MBP polyproteins.
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